Highly coplanar electron transport type small-molecule semiconductor material and preparation method thereof
By designing a fully condensed ring conjugated framework in organic small molecule electron transport materials and introducing strong electron withdrawing groups, the problems of high LUMO energy level and large electron injection barrier are solved, and efficient electron transport and stable device performance are achieved.
Patent Information
- Application Number
- CN202510276523.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-03-10
- Publication Date
- 2025-06-10
AI Technical Summary
The existing organic small molecule electron transport materials have problems such as high LUMO energy level and large electron injection barrier, which limits the improvement of device performance.
By constructing a material design that combines the fully condensed ring conjugated framework with double bonds, the single bond structure in the molecular main chain is eliminated, the conjugated plane configuration is locked, and strong electron-absorbing groups such as lactam, lactone groups and cyano groups are introduced to achieve accurate downward movement of the LUMO energy level.
The LUMO energy level is significantly reduced, making it reach below -4.0 eV, improving the energy level matching with the metal cathode, and improving the electron transmission efficiency and stability of device performance.
Smart Images
Figure CN120118104A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the field of organic semiconductor materials, and particularly to a highly coplanar electron-transporting small molecule semiconductor material and a preparation method thereof. Background Art
[0002] The rapid development of organic electronic devices (such as OLEDs, OPVs) has put forward an urgent demand for high-performance electron-transporting materials. Traditional organic semiconductor materials often have problems such as low electron mobility, poor energy level matching, and insufficient batch stability due to molecular structure defects, which restrict the further improvement of device performance.
[0003] Existing electron-transporting organic semiconductor materials (such as those based on thiophene or benzene ring semiconductor materials) generally have the problem that the free rotation of single bonds in the molecular main chain easily causes the distortion of the conjugated plane, resulting in the hindrance of intramolecular charge delocalization and the disorder of solid-state packing. The conformational isomers generated by the internal rotation of single bonds will significantly increase the energy barrier in the carrier transport process. Therefore, traditional electron-transporting organic semiconductor materials have problems such as a relatively high LUMO energy level and a large electron injection barrier. Therefore, there is still room for improvement in current organic small molecule electron-transporting materials. Summary of the Invention
[0004] The present invention provides a highly coplanar electron-transporting small molecule semiconductor material and a preparation method thereof to solve the problems of relatively high LUMO energy level and large electron injection barrier existing in existing organic small molecule electron-transporting materials.
[0005] In order to achieve the above object, the technical solution adopted by the present invention is as follows:
[0006] A highly coplanar electron-transporting small molecule semiconductor material has the following structural formula:
[0007]
[0008] In the formula, R is any one of straight-chain alkyl groups with 6-16 carbon atoms, or any one of branched-chain alkyl groups with 8-24 carbon atoms.
[0009] Further, the straight-chain alkyl group with 6-16 carbon atoms is n-hexyl, or n-heptyl, or n-octyl, or n-nonyl, or n-decyl, or n-undecyl, or n-dodecyl, or n-tridecyl, or n-tetradecyl, or n-pentadecyl, or n-hexadecyl;
[0010] The branched alkyl group with 8 to 24 carbon atoms is 2-ethylhexyl, or 2-butylhexyl, or 2-hexyloctyl, or 4-hexyldecyl, or 3-hexylundecyl, or 2-octyldecyl, or 2-octyldodecyl, or 3-octyltridecyl, or 2-decyldodecyl, or 2-decyltetradecyl.
[0011] A method for preparing the above-mentioned highly coplanar electron-transporting small molecule semiconductor material, comprising the following steps:
[0012] Step 1: React 1,5-diaminonaphthalene with diethyl ketomalonate, and cyclize under alkaline conditions after the reaction to obtain intermediate a. The structural formula of intermediate a is as follows:
[0013]
[0014] Step 2: React intermediate a with an iodide to obtain intermediate b. Among them, the structural formula of the iodide is RI, where R is any one of the straight-chain alkyl groups with 6 to 16 carbon atoms, or any one of the branched alkyl groups with 8 to 24 carbon atoms; the structural formula of the obtained intermediate b is as follows:
[0015]
[0016] Step 3: React intermediate b with benzodifurandione to generate intermediate c. The structural formula of intermediate c is as follows:
[0017]
[0018] Step 4: React intermediate c with malononitrile to obtain the above-mentioned highly coplanar electron-transporting small molecule semiconductor material.
[0019] Further, in Step 1, dissolve 1,5-diaminonaphthalene and diethyl ketomalonate in acetic acid, react under nitrogen protection at a temperature of 120 °C for 14 to 20 hours, cool to room temperature and spin dry after the reaction; then add an alkaline solution to adjust the pH to 10 to 11, then react at a temperature of 100 °C for 4 to 7 hours, adjust the pH to below 1 with hydrochloric acid after the reaction, and finally filter to obtain a black-purple solid, which is intermediate a;
[0020] Among them, the molar ratio of 1,5-diaminonaphthalene to diethyl ketomalonate is 1.0:(2.0 to 5.0).
[0021] Further, in Step 2, intermediate a and potassium carbonate as a catalyst are added to N,N-dimethylformamide, and stirred for 0.5 to 1.5 hours under nitrogen protection at a temperature of 70 °C; then an iodide is added and the reaction is carried out at 100 °C for 4 to 10 hours. After the reaction is completed, it is cooled to room temperature; then it is extracted with dichloromethane and saturated sodium chloride solution, and the extract is dried with anhydrous magnesium sulfate. Then the dried extract is rotary evaporated and column chromatographed to obtain a blue solid, which is intermediate b;
[0022] Among them, the molar ratio of the intermediate a, potassium carbonate, and iodide is 1.0:(2.0 - 4.0):(2.0 - 6.0).
[0023] Further, in Step 3, intermediate b is added to n-butyric acid as a solvent, and then heated to 130 °C under nitrogen protection. Then benzodifurandione and p-toluenesulfonic acid as a catalyst are added, and stirred for 15 to 20 hours. After stirring is completed, it is cooled to room temperature; then acetone as a solvent is added, and filtration is carried out to collect the solid. Finally, the collected solid is column chromatographed to obtain a black solid, which is intermediate c;
[0024] Among them, the molar ratio of the intermediate b, benzodifurandione, and p-toluenesulfonic acid is 1.0:(0.2 - 0.5):(0.1 - 0.3).
[0025] Further, in Step 4, intermediate c, malononitrile, titanium tetrachloride as a catalyst, and pyridine are added to chloroform as a solvent, and the reaction is carried out at 60 °C for 4 to 8 hours under nitrogen protection. After the reaction is completed, it is cooled to room temperature; then it is extracted with dichloromethane and saturated sodium chloride solution, and the extract is dried with anhydrous magnesium sulfate. Then the dried extract is rotary evaporated and column chromatographed to obtain a black solid, which is a highly coplanar electron-transporting small molecule semiconductor material;
[0026] Among them, the molar ratio of the intermediate c, malononitrile, titanium tetrachloride, and pyridine is 1.0:(5.0 - 20.0):(5.0 - 15.0):(5.0 - 15.0).
[0027] An application of the above-mentioned highly coplanar electron-transporting small molecule semiconductor material as an organic field effect transistor material.
[0028] The present invention proposes to construct a fully fused-ring conjugated backbone combined with double bonds, eliminate the single-bond structure in the molecular main chain, lock the conjugated planar configuration, inhibit molecular vibration and conformational disorder, and enhance the order of π-π stacking, thereby establishing an efficient electron transport channel.
[0029] Among them, the electron injection efficiency of the material highly depends on the matching degree between the LUMO energy level and the work function of the electrode. In the present invention, by introducing three strong electron-withdrawing groups (lactam, lactone group, and cyano group), and utilizing their conjugate induction effect and steric hindrance effect, the accurate downward shift of the LUMO energy level is achieved. Among them, the rigid planar structures of the lactam and lactone groups can be embedded into the main-chain conjugate system, maintaining the molecular planarity while reducing the LUMO; the strong electron-withdrawing property of the cyano group directly participates in the conjugation through covalent bonds, further enhancing the electron affinity. Through electrochemical tests and molecular computational simulations, the synergistic effect of such groups can lower the LUMO energy level below -4.0 eV, significantly improving the energy level matching with the metal cathode (such as Al).
[0030] Compared with polymer semiconductors, the small-molecule materials used in the present invention have a definite molecular weight and chemical structure, which can completely eliminate the batch performance differences caused by different degrees of polymerization of polymer materials. In addition, the design of the fully fused-ring backbone and the oriented substituents avoids the common isomer problems in traditional small-molecule synthesis, ensuring the structural consistency of the materials during synthesis.
[0031] The present invention provides a breakthrough solution for the next-generation organic electronic devices through the synergistic innovation of molecular backbone rigidification, energy level engineering, and synthesis controllability.
[0032] Compared with the prior art, the advantages of the present invention are as follows:
[0033] In the molecular design of the present invention, three strong electron-withdrawing groups, namely lactone, lactam group, and cyano group, are simultaneously introduced, effectively reducing the molecular orbital energy level, achieving stable single-carrier electron transport. At the same time, the design of the fused rings and double bonds in the molecular main chain avoids the internal rotation of carbon-carbon single bonds, and has excellent planarity, with a more regular molecular thin-film morphology. Moreover, the alkyl chains introduced in the side chains can regulate the solution processability of the materials. Through electrochemical energy level tests, the energy level of the present invention is below -4.3 eV, and the single-carrier electron transport ability can be achieved. Description of the Drawings
[0034] Figure 1 It is the ultraviolet-visible-near-infrared absorption spectrum of the highly coplanar electron-transporting small-molecule semiconductor material with the chemical structure of M1 shown in Example 1 of the present invention.
[0035] Figure 2 It is the ultraviolet-visible-near-infrared absorption spectrum of the highly coplanar electron-transporting small-molecule semiconductor material with the chemical structure of M2 shown in Example 2 of the present invention.
[0036] Figure 3 It is the electrochemical energy level test diagram of the highly coplanar electron-transporting small-molecule semiconductor material with the chemical structure of M1 shown in Example 1 of the present invention.
[0037] Figure 4 It is the electrochemical energy level test chart of the highly coplanar electron transport type small molecule semiconductor material with the chemical structural formula M2 shown in Example 2 of the present invention.
[0038] Figure 5 It is the device performance test chart of the highly coplanar electron transport type small molecule semiconductor material with the chemical structural formula M1 shown in Example 1 of the present invention.
[0039] Figure 6 It is the device performance test chart of the highly coplanar electron transport type small molecule semiconductor material with the chemical structural formula M2 shown in Example 2 of the present invention. Detailed implementation manners
[0040] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.
[0041] Example 1
[0042] This example discloses a highly coplanar electron transport type small molecule semiconductor material with the chemical structural formula M1, and its synthesis route is shown in the following reaction formula:
[0043]
[0044] The structural formula M1 of the highly coplanar electron transport type small molecule semiconductor material disclosed in this example is as follows:
[0045]
[0046] In the highly coplanar electron transport type small molecule semiconductor material with the structural formula M1 in this example, R is 4-hexyldecyl, and the structural formula of R is as follows:
[0047]
[0048] The preparation method of the highly coplanar electron transport type small molecule with the structural formula M1 in this example is as follows:
[0049] Step 1: Synthesize intermediate a, and the process is as follows:
[0050] Take 1,5-diaminonaphthalene and diethyl ketomalonate in a molar ratio of 1.0:(2.0 - 5.0). In this example, the mass of 1,5-diaminonaphthalene taken is 2.01 g and the molar amount is 12.7 mmol, and the mass of diethyl ketomalonate taken is 9.14 g and the molar amount is 52 mmol.
[0051] Among them, the structural formula of 1,5-diaminonaphthalene is as follows:
[0052]
[0053] The structural formula of diethyl ketomalonate is as follows:
[0054]
[0055] Dissolve 2.01 g (12.7 mmol) of 1,5-diaminonaphthalene in a two-necked flask A containing 20 ml of glacial acetic acid (acetic acid), and then heat under reflux for 18 hours under nitrogen protection.
[0056] Dissolve 9.14 g (52 mmol) of diethyl ketomalonate in 15 ml of glacial acetic acid, and drop it into the aforementioned two-necked flask A within 0.75 hours, and then heat under reflux for 18 hours under nitrogen protection. The reaction equation is:
[0057]
[0058] After the reaction is completed, rotary evaporate the glacial acetic acid, adjust the pH of the rotary-evaporated product to 10 - 11 with 1 mol / L sodium hydroxide, then add the solution after adjusting the pH into the two-necked flask, heat up to 100 °C and reflux for 5 hours. After the reaction is completed, pour the reactant onto ice, and adjust the pH of the reactant to below 1 with 6 mol / L HCl. The reaction equation is:
[0059]
[0060] Then, perform suction filtration and water washing on the solution after adjusting the pH, and vacuum dry at 70 °C for 16 hours. The obtained black-purple solid is intermediate a, and the yield is 95%. The structural formula of intermediate a is as follows:
[0061]
[0062] Step 2: Synthesize intermediate b, the process is as follows:
[0063] Take intermediate a, potassium carbonate, and iodide in a molar ratio of 1.0:(2.0 - 4.0):(2.0 - 6.0). In this example, 2.58 g (9.71 mmol) of intermediate a, 4.03 g (29.13 mmol) of potassium carbonate, and 13.48 g (38.26 mmol) of iodide are taken.
[0064] Among them, the structural formula of the iodide is RI, and R is any one of straight-chain alkyl groups with 6 - 16 carbon atoms or any one of branched-chain alkyl groups with 8 - 24 carbon atoms. In this example, 1-iodo-2-hexyldecane is selected as the iodide.
[0065] The intermediate a with a mass of 2.58 g and a molar amount of 9.71 mmol and potassium carbonate as a catalyst with a mass of 4.03 g and a molar amount of 29.13 mmol were dissolved in a two-necked flask B containing 50 ml of N,N-dimethylformamide. The reactants were heated to 70 °C under a nitrogen atmosphere and stirred for 0.5 hour.
[0066] Subsequently, 1-iodo-2-hexyldecane with a mass of 13.48 g and a molar amount of 38.26 mmol was added to the two-necked flask B after the above reaction was completed. The reactants in the two-necked flask B were heated to 100 °C and reacted for 5.5 hours. The reaction equation is:
[0067]
[0068] After the reaction was completed, the reactants were cooled to room temperature. Subsequently, the mixture was extracted with dichloromethane to obtain an organic layer extract.
[0069] The extract was then dried with anhydrous magnesium sulfate as a desiccant. Finally, the solvent was removed by rotary evaporation and rotary evaporation through a column. The process of rotary evaporation through a column was as follows: Dichloromethane was removed by rotary evaporation at 30 °C, and then N,N-dimethylformamide was removed by a rotary evaporator at 80 °C.
[0070] The blue solid obtained after rotary evaporation through a column was the intermediate b, and the yield was 13%.
[0071] Step 3: Synthesize intermediate c, and the process is as follows:
[0072] The intermediate b, benzodifurandione, and p-toluenesulfonic acid were taken in a molar ratio of 1.0:(0.2 - 0.5):(0.1 - 0.3). In this example, the intermediate b was taken with a mass of 0.2 g and a molar amount of 0.29 mmol; benzodifurandione was taken with a mass of 0.02 g and a molar amount of 0.1 mmol; p-toluenesulfonic acid was taken with a mass of 0.007 g and a molar amount of 0.03 mmol.
[0073] Among them, the structural formula of benzodifurandione is:
[0074]
[0075] The structural formula of p-toluenesulfonic acid is:
[0076]
[0077] Dissolve 0.2 g of intermediate b with a molar amount of 0.29 mmol and 0.007 g of p-toluenesulfonic acid as a catalyst with a molar amount of 0.03 mmol in a two-necked flask containing 10 ml of n-butyric acid as a solvent. After heating the reactants to 130 °C under nitrogen protection, add 0.02 g of benzodifuran dione with a molar amount of 0.1 mmol.
[0078] Subsequently, heat under reflux for 18 hours. After the reaction is completed, add acetone as a solvent. The reaction equation is:
[0079]
[0080] Then, filter to collect the solid. Finally, subject the collected solid to column chromatography. The black solid obtained after column chromatography is intermediate c, and the yield is 20%.
[0081] Step 4: Synthesize a highly coplanar electron-transporting small molecule semiconductor material with the chemical structure of M1. The process is as follows:
[0082] Take intermediate c, malononitrile, titanium tetrachloride, and pyridine in a molar ratio of 1.0:(5.0 - 20.0):(5.0 - 15.0):(5.0 - 15.0). In this example, 0.032 g of intermediate c with a molar amount of 0.02 mmol is taken; 0.026 g of malononitrile with a molar amount of 0.4 mmol is taken; 0.038 g of titanium tetrachloride with a molar amount of 0.2 mmol is taken; 0.032 g of pyridine with a molar amount of 0.4 mmol is taken.
[0083] Among them, the chemical structure of malononitrile is:
[0084]
[0085] The chemical structure of titanium tetrachloride is TiCl 4
[0086] The chemical structure of pyridine is:
[0087]
[0088] Dissolve 0.032 g of intermediate c with a molar amount of 0.02 mmol in a reaction flask containing 15 ml of chloroform as a solvent. Subsequently, add 0.026 g of malononitrile with a molar amount of 0.4 mmol, 0.038 g of titanium tetrachloride as a catalyst with a molar amount of 0.2 mmol, and 0.032 g of pyridine as a catalyst with a molar amount of 0.4 mmol to the reaction flask.
[0089] Then react at 60 °C for 5 hours under a nitrogen atmosphere. The reaction equation is:
[0090]
[0091] Subsequently, extraction was carried out with dichloromethane and saturated sodium chloride solution to obtain the organic layer extract.
[0092] Next, the extracted organic layer was dried with anhydrous magnesium sulfate.
[0093] Finally, the extracted organic layer was subjected to rotary evaporation and column chromatography. The process of rotary evaporation and column chromatography was to rotary dry dichloromethane and chloroform by rotary evaporation at 50 °C.
[0094] The black solid obtained after rotary evaporation and column chromatography is a highly coplanar electron transport type small molecule semiconductor material with the structural formula M1, and the yield is 60%.
[0095] Example 2
[0096] A highly coplanar electron transport type small molecule semiconductor material with the chemical structural formula M2 has the following synthesis route:
[0097]
[0098] The structural formula M2 of the highly coplanar electron transport type small molecule semiconductor material disclosed in this example is as follows:
[0099]
[0100] In the highly coplanar electron transport type small molecule with the structural formula M2 in this example, R is 2-octyldodecyl, and the structural formula of R is as follows:
[0101]
[0102] The preparation method of the highly coplanar electron transport type small molecule with the structural formula M1 in this example is as follows:
[0103] Step 1: Synthesize intermediate a, and the process is the same as in Example 1;
[0104] Step 2: Synthesize intermediate b, and the process is as follows:
[0105] Take intermediate a, potassium carbonate, and iodide in a molar ratio of 1.0:(2.0 - 4.0):(2.0 - 6.0). In this example, the mass of intermediate a taken is 2.58 g and the molar amount is 9.71 mmol; the mass of potassium carbonate taken is 4.03 g and the molar amount is 29.13 mmol; the mass of iodide taken is 15.63 g and the molar amount is 38.26 mmol.
[0106] Among them, the structural formula of the iodide is RI, where R is any one of straight-chain alkyl groups with 6-16 carbon atoms or any one of branched-chain alkyl groups with 8-24 carbon atoms. In this example, 1-iodo-2-octyldodecane is selected as the iodide.
[0107] Dissolve 2.58 g (9.71 mmol) of intermediate a and 4.03 g (29.13 mmol) of potassium carbonate as a catalyst in a two-necked flask B containing 50 ml of N,N-dimethylformamide. Under a nitrogen atmosphere, heat the reactants to 70 °C and stir for 0.5 hour to dissolve the reactants.
[0108] Subsequently, add 15.63 g (38.26 mmol) of 1-iodo-2-octyldodecane to the two-necked flask B after the above reaction is completed, and heat the reactants to 100 °C for 5.5 hours. The reaction equation is:
[0109]
[0110] After the reaction is completed, cool the reactants to room temperature. Then, extract the mixture with dichloromethane to obtain an organic layer extract. Use anhydrous magnesium sulfate as a desiccant to dry the extract. Finally, remove the solvent by rotary evaporation and perform rotary evaporation through a column. The process of rotary evaporation through a column is as follows: Remove dichloromethane at 30 °C using a rotary evaporator, and then remove N,N-dimethylformamide at 80 °C by rotary evaporation.
[0111] The blue solid obtained after rotary evaporation through a column is intermediate b, and the yield is 13%.
[0112] Step 3: Synthesize intermediate c, and the process is as follows:
[0113] Take intermediate b, benzodifurandione, and p-toluenesulfonic acid in a molar ratio of 1.0:(0.2-0.5):(0.1-0.3). In this example, 0.24 g (0.29 mmol) of intermediate b, 0.02 g (0.1 mmol) of benzodifurandione, and 0.007 g (0.03 mmol) of p-toluenesulfonic acid are taken.
[0114] Among them, the structural formula of benzodifurandione is:
[0115]
[0116] The structural formula of p-toluenesulfonic acid is:
[0117]
[0118] Dissolve 0.24 g of intermediate b with a molar amount of 0.29 mmol and 0.007 g of p-toluenesulfonic acid as a catalyst with a molar amount of 0.03 mmol in a two-necked flask containing 10 ml of n-butyric acid as a solvent. After heating the reactants to 130 °C under nitrogen protection, add 0.02 g of benzodifurandione with a molar amount of 0.1 mmol.
[0119] Subsequently, heat under reflux for 18 hours. After the reaction is completed, add acetone as a solvent. The reaction equation is:
[0120]
[0121] Then, filter by suction to collect the solid. Finally, column chromatograph the collected solid. The black solid obtained after column chromatography is intermediate c, and the yield is 20%.
[0122] Step 4: Synthesize a highly coplanar electron-transporting small molecule semiconductor material with the chemical structure of M1. The process is as follows:
[0123] Take intermediate c, malononitrile, titanium tetrachloride, and pyridine in a molar ratio of 1.0:(5.0 - 20.0):(5.0 - 15.0):(5.0 - 15.0) and add them to 10 mL of chloroform. In this example, 0.038 g of intermediate c with a molar amount of 0.02 mmol is taken; 0.026 g of malononitrile with a molar amount of 0.4 mmol is taken; 0.038 g of titanium tetrachloride with a molar amount of 0.2 mmol is taken; 0.032 g of pyridine with a molar amount of 0.4 mmol is taken.
[0124] Among them, the chemical structure of malononitrile is:
[0125]
[0126] The chemical structure of titanium tetrachloride is TiCl 4
[0127] The chemical structure of pyridine is:
[0128]
[0129] Dissolve 0.038 g of intermediate c with a molar amount of 0.02 mmol in a reaction flask containing 15 ml of chloroform as a solvent. Subsequently, add 0.026 g of malononitrile with a molar amount of 0.4 mmol, 0.038 g of titanium tetrachloride as a catalyst with a molar amount of 0.2 mmol, and 0.032 g of pyridine as a catalyst with a molar amount of 0.4 mmol to the reaction flask.
[0130] Then react at 60 degrees for five hours under a nitrogen atmosphere. The reaction equation is:
[0131]
[0132] Subsequently, extract with dichloromethane and saturated sodium chloride solution to obtain the organic layer extract.
[0133] Next, dry the extracted organic layer with anhydrous magnesium sulfate.
[0134] Finally, subject the extracted organic layer to rotary evaporation and column chromatography. The process of rotary evaporation and column chromatography is to rotary evaporate dichloromethane and chloroform to dryness at 50 degrees.
[0135] The black solid obtained after rotary evaporation and column chromatography is a highly coplanar electron-transporting small molecule semiconductor material with the structural formula M2, and the yield is 60%.
[0136] Example 3
[0137] The following are the measurements of the absorption spectral properties, electrochemistry, and organic field effect transistor performance of the highly coplanar electron-transporting small molecule semiconductor materials prepared in Examples 1 and 2. Among them, the highly coplanar electron-transporting small molecule semiconductor material with the structural formula M1 prepared in Example 1 is named M1, and the highly coplanar electron-transporting small molecule semiconductor material with the structural formula M2 prepared in Example 2 is named M2. The process is as follows:
[0138] Absorption spectral properties of highly coplanar electron-transporting small molecule semiconductor materials M1 and M2
[0139] Figure 1 and Figure 2 are the ultraviolet–visible–near-infrared absorption spectra of the highly coplanar electron-transporting small molecule semiconductor materials M1 and M2 in chloroform solution and on a quartz plate film. From Figure 1 and Figure 2 it can be seen that both the solutions and films of the highly coplanar electron-transporting small molecule semiconductor materials M1 and M2 exhibit a wide absorption range. The maximum absorption edge band value of their film absorption is about 1200 nm. The highly coplanar electron-transporting small molecule semiconductor materials M1 and M2 have broad absorption peaks, covering the visible light and extending to the near-infrared region.
[0140] Electrochemical performance test of highly coplanar electron-transporting small molecule semiconductor materials M1 and M2
[0141] Figure 3 is the electrochemical performance test chart of the highly coplanar electron-transporting small molecule semiconductor material M1 obtained by cyclic voltammetry testing. It shows that through calculation, the LUMO energy level of the highly coplanar electron-transporting small molecule semiconductor material M1 is -4.32 eV.Figure 4 It is the electrochemical performance test chart of the highly coplanar electron-transporting small molecule semiconductor material M2 obtained by cyclic voltammetry testing. The LUMO energy level of the highly coplanar electron-transporting small molecule semiconductor material M2 is -4.34 eV.
[0142] Performance test of organic field-effect transistors of the highly coplanar electron-transporting small molecule semiconductor materials M1 and M2
[0143] Figure 5 and Figure 6 are respectively the output and transfer curves of the organic thin-film transistor devices with the highly coplanar electron-transporting small molecule semiconductor materials M1 and M2 as the semiconductor layer, both showing unipolar electron transport.
[0144] In summary, for the highly coplanar electron-transporting small molecule semiconductor materials M1 and M2 prepared in the above-mentioned Example 1 and Example 2, when the LUMO energy level is less than -4.0 eV, the organic field-effect transistor material can conduct stable electron transport. And the highly coplanar electron-transporting small molecule semiconductor materials obtained by cyclic voltammetry all have LUMO energy levels less than -4.0 eV, and the carrier mobilities obtained from the transfer output curves when M1 and M2 are used as organic field-effect transistors for testing are 3.9×10 -3 cm 2 V -1 s -1 and 1.25×10 -3 cm 2 V -1 s -1 , so they are suitable for use as organic field-effect transistor materials.
[0145] The preferred embodiments of the present invention have been described in detail above in conjunction with the accompanying drawings. The embodiments described in the present invention are only descriptions of the preferred embodiments of the present invention, and do not limit the concept and scope of the present invention. Among the various specific technical features described in the above specific embodiments, they can be combined in any suitable manner without contradiction. As long as such a combination does not violate the idea of the present invention, it should also be regarded as the content disclosed in this disclosure. To avoid unnecessary repetition, the present invention does not further explain various possible combination methods.
[0146] The present invention is not limited to the specific details in the above embodiments. Within the technical concept scope of the present invention and without departing from the design idea of the present invention, various variations and improvements made by those skilled in the art to the technical solutions of the present invention should all fall within the protection scope of the present invention. The technical content claimed by the present invention has been fully recorded in the claims.
Claims
1. A highly coplanar electron transport type small molecule semiconductor material, characterized in that: The structural formula is as follows: In the formula, R is any one of straight-chain alkyl groups having a total carbon atom number of 6 to 16, or any one of branched-chain alkyl groups having a total carbon atom number of 8 to 24.
2. A highly coplanar electron transport type small molecule semiconductor material according to claim 1, characterized in that: The straight-chain alkyl group having a total of 6 to 16 carbon atoms is n-hexyl, or n-heptyl, or n-octyl, or n-nonyl, or n-decyl, or n-undecyl, or n-dodecyl, or n-tridecyl, or n-tetradecyl, or n-pentadecyl, or n-hexadecyl; The branched alkyl group having a total of 8 to 24 carbon atoms is 2-ethylhexyl, or 2-butylhexyl, or 2-hexyloctyl, or 4-hexyldecyl, or 3-hexylundecyl, or 2-octyldecyl, or 2-octyldodecyl, or 3-octyltridecyl, or 2-decyldodecyl, or 2-decyltetradecyl.
3. A method for preparing a highly coplanar electron transport type small molecule semiconductor material as claimed in claim 1 or 2, characterized in that: The following steps are involved: Step 1: react 1,5-diaminonaphthalene with diethyl ketomalonate, and then perform ring closure under alkaline conditions to obtain intermediate a. The structural formula of intermediate a is shown below: Step 2, reacting intermediate a with iodide to obtain intermediate b, wherein the structural formula of the iodide is RI, wherein R is any one of a linear alkyl group having a total number of carbon atoms of 6 to 16, or any one of a branched alkyl group having a total number of carbon atoms of 8 to 24; the structural formula of the obtained intermediate b is as follows: Step 3: reacting intermediate b with benzodifurandione to generate intermediate c. The structural formula of intermediate c is as follows: Step 4: react the intermediate c with malononitrile to obtain the highly coplanar electron transport type small molecule semiconductor material.
4. The method for preparing a highly coplanar electron transport type small molecule semiconductor material according to claim 3, characterized in that: In step 1, 1,5-diaminonaphthalene and diethyl ketomalonate are dissolved in acetic acid, reacted under nitrogen protection at 120° C. for 14 to 20 hours, cooled to room temperature and spin-dried after the reaction; then an alkaline solution is added to adjust the pH to 10 to 11, followed by reacting at 100° C. for 4 to 7 hours, and after the reaction, the pH is adjusted to below 1 with hydrochloric acid, and finally filtered to obtain a black purple solid, which is intermediate a; Wherein, the molar ratio of the 1,5-diaminonaphthalene to diethyl ketomalonate is 1.0:(2.0-5.0).
5. The method for preparing a highly coplanar electron transport type small molecule semiconductor material according to claim 3, characterized in that: In step 2, the intermediate a and potassium carbonate as a catalyst are added to N,N-dimethylformamide, and stirred for 0.5 to 1.5 hours under nitrogen protection and 70°C; then iodide is added and reacted at 100°C for 4 to 10 hours, and cooled to room temperature after the reaction is completed; then, the extract is extracted with dichloromethane and saturated sodium chloride solution, and the extract is dried with anhydrous magnesium sulfate, and the dried extract is then subjected to rotary evaporation to obtain a blue solid, which is the intermediate b; Wherein, the molar ratio of the intermediate a, potassium carbonate and iodide is 1.0:(2.0-4.0):(2.0-6.0).
6. The method for preparing a highly coplanar electron transport type small molecule semiconductor material according to claim 3, characterized in that: In step 3, the intermediate b is added to n-butyric acid as a solvent, and then heated to 130° C. under nitrogen protection, followed by adding benzodifurandione and p-toluenesulfonic acid as a catalyst, and stirring for 15 to 20 hours. After stirring, the mixture is cooled to room temperature; acetone as a solvent is then added, and solids are collected by suction filtration, and finally the collected solids are passed through a column to obtain a black solid, which is the intermediate c; Wherein, the molar ratio of the intermediate b, benzodifurandione and p-toluenesulfonic acid is 1.0:(0.2-0.5):(0.1-0.3).
7. The method for preparing a highly coplanar electron transport type small molecule semiconductor material according to claim 3, characterized in that: In step 4, the intermediate c, malononitrile, titanium tetrachloride as a catalyst and pyridine are added to chloroform as a solvent, and the reaction is carried out under nitrogen protection and at a temperature of 60° C. for 4 to 8 hours. After the reaction is completed, the reaction is cooled to room temperature; then, the mixture is extracted with dichloromethane and a saturated sodium chloride solution, and the extract is dried with anhydrous magnesium sulfate. The dried extract is then subjected to rotary evaporation through a column, and the obtained black solid is a highly coplanar electron transport type small molecule semiconductor material; Wherein, the molar ratio of the intermediate c, malononitrile, titanium tetrachloride and pyridine is 1.0:(5.0-20.0):(5.0-15.0):(5.0-15.0).
8. Use of the highly coplanar electron transport type small molecule semiconductor material as claimed in claim 1 or 2 as an organic field effect transistor material.